Restaurants and cafes generate large quantities of heat in the course of their operation. The heat results from the combustion of fuel or the operation of electrical resistance heaters, or both, used in the heating or cooking of food.
In cooking and heating processes, various gases, with or without particulates as in smoke, are generated. These gases are collectively referred to herein as "fumes" and may include one or more of gases of combustion resulting from the combustion of the fuel used to heat or cook the food, volatiles released by the food being heated or cooked, and water vapor from boiling or steaming containers or food, smoke resulting from the heating or cooking process, or resulting from the burning of food or parts thereof as, for example, the burning of fat released while cooking a steak over a grill.
As is well known, these fumes are typically exhausted from the vicinity of the range using an exhaust hood which overlies the range and which is connected to an exhaust duct leading to a point of discharge of the fumes. An exhaust fan is typically connected to the duct to create low pressure therein so that fumes rising from the range, and a certain amount of ambient air, are drawn into the exhaust hood and ultimately discharged elsewhere.
Upon consideration, those skilled in the art will recognize that the fumes being exhausted are typically at a temperature elevated well above ambient. To the extent that the fumes are simply discharged, their heat content is wasted. It has therefore been proposed to use the heat contained in the fumes for other purposes as, for example, in providing hot water which will typically be required by a restaurant operation for the washing of dishes and hands as well as for the operation of lavatories and the like.
At the same time, it has been recognized that grease contained in the fumes being exhausted must be disposed of. Current standards of the Underwriters Laboratory require the removal of at least four grams of grease for every gram of grease left on the typical filter employed in such systems during the exhausting of fumes.
The present invention is directed to providing a system that utilizes waste heat in the fume stream emanating from a range to provide hot water while at the same time removes sufficient grease from the stream so as to meet the standards of Underwriters Laboratory.